Loestrin 24 Fe
Loestrin 24 Fe
Generic Name
Loestrin 24 Fe
Mechanism
- Hormonal suppression
- *Ethinyl estradiol* (35 µg) mimics estradiol, forming a negative‑feedback loop that inhibits pituitary gonadotropin release.
- *Drospirenone* (4 mg) is a progesterone‑analog with anti‑androgenic and antimineralocorticoid activity, further suppressing follicular maturation and thickening cervical mucus.
- Iron mitigation of menstrual loss
- 3 consecutive iron‑containing tablets (≈ 40 mg elemental iron) prevent or correct iron‑deficiency anemia that can result from chronic menstrual bleeding.
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Pharmacokinetics
| Parameter | Details |
| Absorption | Rapid oral absorption; peak serum estradiol at ~1 h post‑dose. |
| Metabolism | Estradiol → hepatic conjugation (glucuronide, sulfate). Drospirenone → hepatic CYP3A4-mediated oxidation. |
| Half‑life | Estradiol: ~3 h; Drospirenone: ~10 h (clinical effect ~36 h). |
| Protein binding | Estradiol 85 %; Drospirenone 45 %. |
| Excretion | Primarily via feces; 12 h in plasma ~10 % of dose. |
| Iron | Ferrous fumarate → absorbed in duodenum; follows normal iron‑homeostasis pathways. |
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Indications
- Contraception in women 15–45 y (FDA‑approved).
- Menstrual cycle regulation: for amenorrhea, dysmenorrhea, and irregular bleeding.
- Acne vulgaris: anti‑androgenic effect of drospirenone improves hormonal acne.
- Iron-deficiency anemia, especially in women with clinically significant menstrual blood loss.
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Contraindications
| Category | Specifics |
| Absolute Contraindications |
• Known or suspected pregnancy • History of thromboembolic disease (DVT, PE) • Recent ischemic stroke or myocardial infarction • Uncontrolled hypertension (>140/90 mmHg) • Active hepatic disease or jaundice • Migraine with aura • Smoking ≥35 y > 35 y of age or • Hormone‑sensitive cancers (breast, endometrial, ovarian). |
| Relative Contraindications |
• Mild hypertension; uncontrolled DM; migraine without aura if moderate risk • Renal disease may limit iron tolerability. |
| Warnings |
• Increased risk of VTE, stroke, MI is dose‑ and age‑dependent. • Hemorrhagic stroke risk ↑ in patients with uncontrolled HTN. • Avoid in women with severe hepatic impairment or liver failure. • Iron‑related GI upset (nausea, constipation) can exacerbate constipation. |
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Dosing
| Day | Tablet Content | Instructions |
| 1–21 | Drospirenone 4 mg + Ethinyl estradiol 35 µg | Take 1 tablet daily at same time each day. |
| 22–24 | Iron (≈ 40 mg elemental) | Take 1 tablet daily; can be taken at any time, preferably with food to improve absorption and reduce GI upset. |
| 25–31 | Placebo | Follow normal pill‑free interval. |
• Start date: day 1 (first active pill). For those beginning in the middle of a cycle, start immediately and resume scheduled cycle after 21 days.
• Missed pill: If ≥2 h after scheduled dose, take as soon as remembered, then resume normal timing. 2‑day interregimen bleed risk if 3‑day drop-out occurs before day 9.
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Adverse Effects
| Adverse effect | Frequency | Notes |
| Common | ||
| Nausea and vomiting | 3–5 % | Usually transient, episiotrophic with iron. |
| Headache | 4–10 % | Avoid during pregnancy; check for migraines. |
| Breast tenderness | 2–5 % | May improve with continuous cycle use. |
| Mild anemia (iron‑related) | <1 % | Monitor CBC, especially after prolonged use. |
| Serious | ||
| Venous thromboembolism (VTE) | 35, smoking. | |
| Stroke / MI | Rare | Avoid in women with risk factors. |
| Severe allergic reaction (anaphylaxis) | Very rare | Avoid if history of drug allergy. |
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Monitoring
- Baseline
- Weight, height, BMI
- Blood pressure (≥3 readings)
- CBC & iron studies (Hb, ferritin, transferrin saturation)
- Liver function tests if hepatic disease risk
- Follow‑up
- BP and weight each visit (3–6 mth).
- CBC + ferritin every 6 mth for women with heavy menses or disease.
- Assess for signs of thrombosis: leg swelling, chest pain, dyspnea.
- Evaluate efficacy: menstrual pattern, acne score, OCP adherence.
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Clinical Pearls
1. Iron Advantage – The 3‑day iron regimen mitigates menstrual blood loss‑induced anemia, making Loestrin 24 Fe ideal for women with iron‑deficiency risk or heavy bleeding.
2. Anti‑Androgenic Benefit – Drospirenone’s antimineralocorticoid and anti‑androgenic properties yield better acne control and lower fluid retention compared to other second‑generation OCPs.
3. 24‑Day Cycle Convenience – The extended interval allows transition to a single‑dose “flash‑dose” 24‑hour regimen for rapid start or missed‑pill cover, albeit with a short drop‑in period.
4. Iron Timing Matters – Taking iron tablets with a meal increases absorption and reduces GI side effects; separation from estrogen/progestin tablets is not essential.
5. Clostridium difficile – Oral contraceptives, including Loestrin 24 Fe, have been reported to increase infection risk in predisposed individuals; monitor for severe diarrhea.
6. Pad Use – Women with heavy menses may still benefit from extra protection during the 7‑day hormone‑free interval, despite the iron component.
7. Pregnancy + Iron – If accidental pregnancy occurs, iron tablets continue without estrogen/progestin until pregnancy test resolution; counseling for early prenatal iron is essential.
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• *This drug card offers a concise, evidence‑based reference for medical students and clinicians, incorporating key pharmacology terms and clinically actionable insights for the optimal use of Loestrin 24 Fe.*